Gun perforators for wells



May 5, 1959 T. o. ALLEN GUN PERFoRATpRs FOR WELLS -Filed Dec. 14, 1953 F'IG. 5.

INVEN TOR. Thomas 0. Allen,

A TTRN United States Patent O 2,884,836 GUN PERFoRAroRs FOR WELLS Thomas O. Allen, Houston, Tex., assignor, by mesne assignments, to Jersey Production Research Company, Tulsa, Okla., a corporation of Delaware Application December 14, 1953, Serial No. 397,955

13 Claims. (Cl. 89-1) The present invention relates to guns for perforating pipe in oil wells and the like. More particularly, the invention is directed to guns which are small enough to run through tubing in a well for perforating casing beneath the tubing. In its more specific aspects, the invention is directed to an improved bullet for use in gun perforators.

The present invention may be briefly described as an arrangement for perforating casing and the like in oil and gas wells which comprises an elongated tubular body small enough to be run into the well through the tubing as desired or directly inside the casing to be perforated. Sockets are arranged in the body and the body isprovided with gun barrels mounted in the sockets. Each barrel has a bullet arranged therein adapted when projected from the gun barrel to perforate the casing. Each of the bullets is provided with an internal chamber and rupturable or frangible means, which are destrnctible, are arranged in the chamber separating the chamber into a first compartment and a second compartment. A body of a first reactive chemical is arranged in the first compartment and a body of a second reactive chemical is arranged in the :second compartment. These bodies are adapted to explode when brought together. The rupturable separating means are adapted to bring the chemicals together after the bullet has been fired. The bullet is constructed of a nose section and a body section and at least a portion of the 'body section is adapted to be discharged on mixture of the chemicals in a direction opposite to the normal travel of the bullet to cleanse the perforation passage made by the bullet.

The bullet may be provided with a rupturable means which may lbe a frangible, destructible wall member which separates the chamber into two compartments. It is also contemplated that the compartments; may be contained in a capsule containing the chemicals and the capsule inserted or snapped into the chamberprior to loading the bullet into the gun. Thus, the capsule may be simply snapped into place in the chamber on removing either the nose section or by opening the tail end of the bullet depending on the type of the 'bullet and the location of the chamber therein. These capsules may be constructed `'similar to the medicinal capsule but provided with a frangible or rupturable wall to allow comrningling of the reactive chemical. The frangible, destructible wall member may be a high melting point wax, such as a parathnic wax, having a melting point between 100 F. and 250 F. or the frangible, destructible wall member may be a low melting point alloy comprised of bismuth, such as Lipowitzs metal, Woods metal, Roses metal and the like alloys which contain bismuth as a major component. The frangible, destructible wall member may also be comprised of tin or other thin frangible metal which is designed to be pierced readily by a pointed member arranged in proximity to the wall member.

The present invention will be further illustrated by reference to the drawing in which:

Fig. l is a fragmentary view showing a portion of a tubular body member lowered in a well casing in which is arranged a plurality of gun barrels containing bullets in accordance with the present invention;

Fig. 2 shows the bullet of the present invention after being fired into the formation, sand, or strata to be perforated;

Fig. 3 shows the perforation formed by the apparatus of the present invention;

Fig. 4 is a modification of the apparatus of Figs. l and 2;

F Fig. 5 is a further modification of the apparatus of Fig. 6 illustrates one rupturing means for a frangible, destructible wall member;

Fig. 7 illustrates a ibullet of the present invention with a means for lling the compartments; and

Fig. 8 shows another embodiment of the bullet of the present invention with means for filling the compartments and illustrating means for holding the sections of the bullet together.

Referring now to the several figures of the drawing in which identical numerals will be designated to identify identical Iparts, numeral 11 designates a tubular body member adapted to be lowered in a casing or through a tubing in a casing and numeral 12 designates a casing arranged below the tubing not shown. Arranged in sockets 14 are a plurality of ygun barrels 15 which may be threadably engaged with threads 16 with the carriage or body member 1l. The rear portion 17 of the sockets 14 comprises a body chamber which may be filled with a high explosive 18 which is suitably detonated by means of igniter wires 19 connected to an electrical conductor 20.

Arranged in the gun barrel l5 is a bulle-t generally indicated by the numeral 21 which is comprised of nose section 22 and a separable body section 23. The body section 23 is provided with a chamber 24 which is designed to receive capsules or containers 26 and 27. The capsules 26 and 27 are adapted to contain reactive chemicals which explode on coming into contact with each other.

'Referring now to Fig. 2, it will be seen that the explosive 18 in the chamber 17 has been detonated to cause the bullet 21 to be fired into the sand, strata, or formation 23 to form a perforation 29 through the cement 30 and the casing 12 and to penetrate the sand 28. It will be noted that the perforation 29 is filled with debris which is comprised of formation material, gun powder and .other materials which flow into the perforation 29 immediately after the bullet has formed a path of travel into the sand 28.

In accordance with the present invention, the capsules 26 and 27 are designed to be ruptured or melted after the bullet 21 has penetrated the formation 28 and formed thev perforation 29. The melting is accomplished by providing a capsule or container which is easily readily melted at temperatures encountered in the formation 28. Assuming for the purpose of this description that the capsules 26 and 27 are comprised of a bismuth containing alloy, the admixture of the chemicals in capsules 26 and 27 formed an explosive mixture which caused the body section 23 to be blown back out of the perforation 29 as shown more clearly in Fig. 3. By blowing the section 23 out of the perforation 29, the debris accumulating in the perforation 29 is cleaned out therefrom allowing oil ow into the perforation 29 as indicated by the arrows and up the casing 12 through the tubing, as desired.

Referring now to Fig. 4, it will be seen that a modified bullet 40 is provided with a chamber 41 which is adapted to receive capsules 26 and 27 containing reactive chemie,

3 cals. 41 fis provided with a ball 45 which may :be readily blown from the bullet 40 on admixture of the reactive -chemicals in capsules 26 and 27.

A modification of the device of Fig. 4 is shown in Fig. 5 in which a bullet 50 is shown red into the formation or sand 28 and a slug 51 has been blown backward out of the perforation 29 to clear a path 51 through the perforation 29. It will be noted in the modification of Fig. 5 which is identical to Fig. 4 except that a slug 51 replaces the ball 45 and the perforation 29 is not completely cleared of debris which originally filled the perforation 29. However, by forming a path through the debris in the perforation 29, the unconsolidated debris in the perforation 29 may be readily cleared from the perforation 29 by virtue of being weakened by passage through v the plug of slug 51 or ball 45 so that well uids may force the remaining part of the debris from the plugged perforation 29.

Referring now to Fig. 6, a bullet 60 is provided with a nose section 61 and a body section 62 which `is arranged in chamber 63 which is separated into compartments 64 and 65 by a franglible wall member 66. Arranged in piercing position with the frangible wall member 66 is a rupturing member or sharp pointed spear 67 which on impact of the nose section 61 of bullet 60 causes piercing of the member 66 and allows reactive chemicals in compartments 64 and 65 to be readily admixed and to cause a sufficiently violent explosion to blow the body section 62 backward through' a perforation, like 29, and clear same of plugging debris which may have accumulated therein.

The bullet 60, like the other several embodiments, is comprised of nose sections and body sections arranged to be easily separated at their point of juncture 68.

In the embodiment of Fig. 6 the nose 61 and the body section 62 may be interconnected by suitable metallic materials of lesser strength than the nose section 61 or the body section 62 such that on impact the member 67 may pierce the member 66 and allow mixture of the reactive chemicals. Thus the point of connection may suitably be a bellows-like arrangement.

The chamber in the improved bullet may suitably be arranged adjacent the nose section or adjacent the tail end of the bullet for filling the chamber with capsules containing reactive chemicals. Thus, the separable nose section may be removed and the capsules placed in the chamber and the nose section re-connected to the body section or the tal or back end of the bullet may be removable for filling the chamber.

Referring now to Fig. 7, a bullet 70 is provided with a nose section 71 and a body section 72. Arranged in the body section 72 is a chamber 73 which is separated into compartments 74 and 75 by a rupturable wall member 76. The chamber 73 has a ball 77 arranged adjacent the compartments 74 and 75 in the space 73a. The chamber 73 is closed by a closure 78 which may be threadably attached to the bullet 70 by means of mating threads 79. The two compartments 74 and 75 may be filled separately through conduits 80 and 81 which are closed and sealed by caps 82 and 83 after the compartments 74 and 75 have been filled with reactive chemicals and prior to threading of the member 78.

- In the instance of Fig. 8, a bullet 90 is provided with a separable nose section 91 and a body section 92 which is provided with a chamber 93 in which is arranged compartments 94 and 95 separated by a rupturable wall member 96. The nose section 91 has a sleeve section 97 which is insertable in the body section 92 and is held in connection with the body section 92 by shear pins or frangrible means 98. The compartments 94 and 95 are provided withconduits 99 and 100, respectively, which project into a space 101 immediately behind the nose section 91. The conduits 99 and 100 are suitably closed and sealed The tail of the bullet adjacent the compartment` by caps 102 and 103 which may be threadably connected to the conduits 99 and 100. f

With respect to Fig. 7, it'will be seen that the cornpartments 74 :and 75 may be filled by removing the member 78 and opening the caps 82 and 83 and connecting the conduits 80y and 81 to a suitable source of the reactive chemicals. Likewise, with respect to the device of Fig. 8, the nose section 91 may be separated from the body section 92 and the compartments 94 and 95 lled through the conduits 99 and 100 on removing the caps 102 and 103 and connecting the conduits 99 and 100 to a separate source of reactive chemicals following which the caps are replaced and the nose section 91 connected by the frangible -means 98 to the body section 92.

As shown clearly in the several gures of the drawing,

v the bullet separates only into two portions without fracturing, at least a portion of the body section sepa-rating from the bullet and being discharged back through the perforation and cleaning same of unconsolidated debris. In the present invention two different chemicals are designed to be placed in intimate contact to cause violent reaction. These chemicals may be separated by a high melting point wax which may be melted by the bottom hole temperature of the well after the bullet is tired into the formation. Illustrative but not exclusive of chemical combinations which may be useful in the practice of the present invention may be mentioned pairs of chemicals which would be placed in the two compartments of the improved bullet of the present invention for admixture with each other: alcohol and calcium permanganate, metallic sodium and water, metallic sodium and a dilute aqueous solution of hydrochloric acid, aluminum powder and concentrated sodium hydroxide, 90% hydrogen peroxide and manganese dioxide, 84% of perchloric acid and -aniline, 84% perchloric acid and hydrocarbon, and the like.

There are many other combinations of chemicals which may be used to produce a suflicient explosive or to generate sufl'ciently high pressure gases to force at least a portion of the bullet out of the hole. The two chemicals are separated so as to prevent a premature explosion.

Thus the well temperature, the temperature of the initial perforating explosion and/or pressure may set off the reaction which is timed such that after the bullet has penetrated as far as it will in the formation or sand at least a portion of the body section of the bullet will be tired backward in a direction opposite to the normal travel of the bullet, through the perforation which has been formed, back into the well bore.

The debris which forms in the perforations is relatively unconsolidated but forms a solid plug of the formation material, gun powder, and other materials, such as mud, which may be in the well during gun perforations. This material follows the bullet almost instantaneously as it enters the formation. It may be understood that such plugging even though of unconsolidated material will impede the ow and at least restrict the llow of oil into the well. The present invention provides for deeper and cleaner perforations in formation sand or strata since the backward charge of the body section of the bullet will cause the nose of the bullet to penetrate even more deeply in the formation and also clean the perforation allowing increased flow of oil into the well.

The nature and objects of tbe present invention having been completely described and illustrated, what I wish to claim as new and useful and to secure by Letters Patent is:

1. An arrangement for perforating casing in oil wells and the like, comprising, in combination, an elongated tubular body small enough in diameter to enable it to be run into the well inside the casing to be perforated, sockets in said body and gun barrels mounted in said sockets, each barrel having a bullet therein adapted when projected from the gun barrel to perforate the casing and form a passage into the formation, each bullet being provided with an internal chamber, a meltable wall member in said chamber separating the chamber into a first compartment and a second compartment, a body of a rst reactive chemical in said irst compartment and a body of a second reactive chemical in -said second compartment, said bodies being adapted to explode when brought together, said meltable wall member being meltable at temperatures between 100 and 250 F. and adapted to bring together said chemicals after said bullet has been fired to perforate the wall of the casing and to penetrate a formation pierced by the well, said bullet being composed of a nose section and a body section, said `sections being separable, said bullet separating only into its nose section and body section after mixing of said chemicals, at least a portion of said body section cleaning out the perforation passage on admixture of said chemicals by discharging said portion of said body section through the perforation passage in a direction opposite the normal travel of said bullet.

2. Apparatus for forming clean perforations in a well bore comprising -a bullet having a nose section and a body section dischargeable into the wall of said well bore and forming a perforation passage therein, at least a portion of said body section being separable from the nose section after discharge of the bullet, said body section having an internal chamber, destructible means in said chamber separating said chamber into a rst compartment and a second compartment, a body of rst reactive chemical in said first compartment and a body of second reactive chemical in said second compartment, said bodies being adapted to explode when brought together, said destructible separating means being adapted to bring together said chemicals yafter said bullet has been discharged into the wall of the well bore and penetrated a formation, said bullet having perforation cleaning means comprised of said body section, said bullet separating only into its nose section and body section after mixing of said chemicals and said perforation cleaning means comprised of said body section cleaning out said perforation passage by discharging into 4and through said passage in a direction opposite to the direction of travel of said bullet, said destructible separating means being formed of a material which is destroyed after the bullet has penetrated said formation.

3. Apparatus in accordance with claim 2 in which said destructible separating means is a meltablc wall member having a melting point between 100 and 250 F.; and corresponding to the temperature of a particular formation to bc penetrated.

4. Apparatus in accordance with claim 2 in which said destructible means comprises a frangible separating wall.

5. Apparatus in accordance with claim 2 in which said destructible means is a sharp-pointed rupturing member adapted to be driven through a frangible separating wall.

6. Apparatus in accordance with claim 2 in which said cleaning means comprises a projectile arranged in and separable from said body section.

7. Apparatus in accordance with claim 6 in which said projectile is a ball.

8. Apparatus in accordance with claim 6 in which said projectile is a slug.

9. Apparatus in accordance with claim 2 in which said internal chamber is defined by said body section.

10. An arrangement for perforating casing in oil wells and the like comprising, in combination, an elongated tubular body small enough in diameter to enable it to be run into the well inside the casing to be perforated, sockets in said body and gun barrels mounted in said sockets, each barrel having a bullet therein adapted when projected from the gun barrel to perforate the casing and form a passage into the formation, ea-ch bullet being provided with an internal chamber, meltable insertable capsules in said chamber, a body of a rst reactive chemical in one of said capsules and a body of a second reactive chemical in another of said capsules, said bodies being adapted to form an explosive mixture when brought together, said meltable capsules being meltable at temperatures between and 250 F.; and adapted to bring together said chemicals after said bullets have been tired to perforate the wall of the casing and to penetrate a formation pierced by the well, said bullet being composed of a nose section and a body section, at least a portion of said body section being separable from the nose section, Vsaid bullet separating only into its nose section and body section after mixing of said chemicals and said body section cleaning out said perforation passage by discharging on admixture of said chemicals in a direction opposite to the direction of normal travel of said bullet.

11. Apparatus in accordance with claim 2 in which the destructible separating means is a high melting point parafnic wax having a melting point between 100 and F.

l2. Apparatus in accordance with claim 2 in which the destructible separating means is a low melting point bismuth alloy having a melting point between 100 and 150 F.

13. Apparatus in accordance with claim 2 in which the destructible separating means is a tin wall which is adapted to be destroyed on impact of the bullet in the formation by -a sharp pointed member arranged in said bullet in wall destroying proximity.

References Cited in the file of this patent UNITED STATES PATENTS 305,881 Bachelder Sept. 30, 1884 878,369 Fuster Feb. 4, 1908 1,174,925 Arndt Mar. 7, 1916 1,284,032 Allen NOV. 5, 1918 1,298,500 Hardel Mar. 25, 1919 1,585,664 Gilman May 25, 1926 2,307,729 Foster Jan. 5, 1943 2,406,135 Chavez Aug. 20, 1946 2,454,281 Hicks NOV. 23, 1948 2,578,726 Moore Dec. 18, 1951 

